An in vitro model of the chicken gastrointestinal tract with special emphasis to the cecal microbiota

An in vitro model of the upper gastroin-testinal tract as well as the chicken cecum was developed to have a predictive tool for estimating the production performance of animals by analyzing the feeding value of a certain diet. The upper gastrointestinal tract con-sists of a batch type model, whereas the cecal model is comprised of 4 semi-continuous connected vessels inocu-lated with cecal or fecal microbes. The upper gastroin-testinal tract and cecal simulations were both run with a corn-and a wheat-based diet to simulate 2 typical feed types. Samples were collected after the 5-h cecal simulations and aliquots were frozen to assess inoculum stability. The microbiota was analyzed by 16S rRNA gene sequencing, whereas short chain fatty acids as microbial metabolites were analyzed by using gas chromatography. As expected, some significant differences in microbial abundance after simulation between the cecal and fecal slurry samples (P = 0.001) were detected, as well between the fresh and frozen status (P = 0.001), hence simulations inoculated with cecal and fresh samples being more diverse. For the measured metabolites, almost all of them increased (P < 0.05) significantly when comparing fresh and frozen inoculum. The present chicken intestinal in vitro model represents a rapid sys-tematic screening system for studying dietary related microbial changes and reducing the need of animal sacri-fice for experimentation.